DNA Probes

• A DNA probe, is a short, single-stranded section of DNA that has a 'label' attached making it easily identifiable. The probe 'hybridises' with sections of DNA which are complementary to it.
• DNA probes can be used to detect the alleles of specific genes. They can be used to detect the alleles of specific genes. They can be used to find:

  • inherited disorders
  • drug responses
  • health risks
• DNA can be made single stranded for probes to bind by breaking the hydrogen bonds with:

  • heat
  • alkaline solution
• Genetic Screening:

  1. A few cells are taken by biopsy
  2. DNA is extracted and if necessary amplified by PCR
  3. DNA is labelled by a fluorescent chemical
  4. The DNA is denatured
  5. The single strand is added to a microarray and mixed for a few hours. DNA that has a complementary sequence to any of the probes fixed to the microarray will hybridise the probes by complementary base pairing
  6. Then washed with buffer, to wash away excess
  7. It is then illuminated with UV, any spots which the DNA has hybridised will be seen.
  8. The locations of the fluorescent spots, are matched with the name of the probe's allele, giving the patient's genetic profile.